Replacement for OMNIE Room Sensor 12Vdc (4 Core, believed to be ModBus RS485)

Hi, I have a burnt out Room Sensor on my underfloor heating. It is almost 10 years old (installed 2017) and looks like one of the grounding wires from the shielded 4 core cable wasn't insulated and must have eventually touched another wire and caused sparks. I have checked all the other room sensors and they are wire/insulated as per the instructions. My issue is that I cannot find a replacement sensor like this. I have contacted OMNIE but they went into Administration in 2024 and Nu-Heat who took on their brand have been no help, saying they know nothing about old products and just told me Salus made some of OMNIE's old parts. I contacted Salus but they say they only made the normal 230V thermostats and did not know who made any like the one I am trying to replace and could provide no further assistance.

So can anyone advise where I can purchase a replacement like this please?

I have attached a photo and I believe it is a 12V dc, 4 core (possibly ModBus RS485 although that has simply come up through google searching) and is connected by belden 4 core cable to a wiring centre model A00600304. If it helps, the system I have, with that sensor and wiring centre can be seen here https://cdn1.omnie.co.uk/wp-content/uploads/20180425101616/IM-ONC-02-Install-Manual-WiFi-Version.pdf

I am not an electrician or heating engineer but have a little knowledge of both and can follow basic instructions if there is some sort of work around to be able to control the underfloor heating in that room again but ideally I would just like to replace the room sensor.
Thank you.

If the damage was caused by the plug/socket melting, it’s not impossible that the actual sensor board is OK. Have you tried dismantling it, to look at the board?

Have you tried Ebay? Or perhaps another manufacturer, eg Honeywell, Wiser, et al?

endecotp said:

If the damage was caused by the plug/socket melting, it’s not impossible that the actual sensor board is OK. Have you tried dismantling it, to look at the board?

Click to expand...

Thanks but the corner of the board is so damaged it has disintergrated along with 2 of the 5 connections - see pic below

CountryFan said:

Have you tried Ebay? Or perhaps another manufacturer, eg Honeywell, Wiser, et al?

Click to expand...

Thanks, I have searched high & low on Ebay and they only seem to have the 230V digital display thermostats, not the low voltage modbus ones (at the moment anyway). I had contacted Salus and Whisper before posting on DIYnot. Salus were no help but a chap at Whisper called Paul has now come back to me and has been amazingly helpful. He gave me a call and told me that Whisper only started working with OMNIE some time after my product was discontinued. However, he had taken the time to reach out to a friend of his who had previously worked for OMNIE, so he could find out if there were any other compatible products.

Unfortunately, he confirmed that type of setup has been abandoned so it is highly unlikely I will find a replacement unless someone happens to sell off parts to an old system, or I know someone who is able to programme a generic modbus board. He then took the time to talk me through some alternative “work arounds”. I was on the phone with him for more than 30minutes and he answered a load of questions for me….he was SO helpful and I am VERY grateful! Basically, I am going to swop out the sensor for that room, which I would like to remain individually controllable, for the one in the utility room, which I will then add to one of the other zones instead. So the system will have one less zone overall but it will all still work and that important room will still be controllable individually. He had alternative suggestions but this was the easiest and costs nothing. In the meantime, I can keep an eye on Ebay for anyone selling off old kit which may be compatible. If anyone knows any sites other than Ebay where people sell old heating tech, I’d been keen to try them.

If too many more go wrong it seems eventually the solution will be to replace the wiring centres and modbus sensors with a RF/Wi-fi system ie all new “electrical/wi-fi controls” but the wet plumbing, manifolds etc will remain....Paul was in no way pushing this but I think I would soon get annoyed with one set of controls for part of the system and other set for the rest.....